//https://leetcode.cn/problems/reverse-linked-list/ 
/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* reverseList(ListNode* head) {
       if(head==nullptr || head->next==nullptr)return head;
       
       ListNode* newhead=reverseList(head->next);
       head->next->next=head;
       head->next=nullptr;

       return newhead;
    }
};
